A large number of sex differences in the central nervous system of vertebrates have now been described. Such morphological dimorphisms may underlie well documented sex differences in behavior, in susceptibility to certain drugs, and in the incidence of some human mental disorders including autism, depression and schizophrenia. In many cases, neural sex differences have been shown to be due to gonadal steroid hormones acting early in development. However, the cellular and molecular mechanisms governed by hormones in the developing nervous system are not well understood. The long range objective of the candidate is to identify cellular and molecular mechanisms of sexual differentiation in the nervous system. A simple neuromuscular system which is sexually dimorphic in many mammals has proven to be a valuable model system for identifying basic principals underlying the development of neural sex differences. Motoneurons of the spinal nucleus of the bulbocavernosus (SNB) of rodents innervate striated muscles of the perineum. The number of SNB motoneurons and the survival of SNB target muscles depend on exposure to androgen during perinatal development. It has been demonstrated that a neurotrophic molecule, ciliary neurotrophic factor (CNTF), can mimic some of the effects of androgen in this system. Moreover, receptors to CNTF are present in the SNB system during the period of sexual differentiation. This raises the possibility that androgenic hormones and neurotrophic factors may interact to cause sex differences in the SNB and elsewhere. The identification of such a mechanism would represent a breakthrough in our understanding of the development of neural sex differences and would identify novel actions of neurotrophic factors. The candidate for this Independent Scientist Award is an associate professor in the Psychology Department at the University of Massachusetts; her teaching load is substantial. She is a member of the Neuroscience and Behavior program and enjoys the support of a very cohesive and active Neuroendocrine Group. The award would allow her time to interact more with students in the lab and with colleagues, to pursue new areas of research, and to develop more fully as a research scientist. In particular, the candidate will gain training in electron microscopy and in "differential display", which will allow the identification of genes regulated by hormones and trophic factors in the SNB neuromuscular system.